Design and Synthesis of Phthalocyanine-Sensitized Titanium Dioxide Photocatalysts: A Dual-Pathway Study

Phthalocyanine-sensitized TiO2 significantly enhances photocatalytic performance, but the method of phthalocyanine immobilization also plays a crucial role in its performance. In order to investigate the effect of the binding strategy of phthalocyanine and TiO2 on photocatalytic performance, a dual-pathway study has been conducted. On the one hand, zinc-tetra (N-carbonylacrylic) aminephthalocyanine (Pc) was directly grafted onto the surface of Fe3O4@SiO2@TiO2 (FST). On the other hand, Pc was immobilized on a silane coupling agent ((3-aminopropyl) triethoxysilane) grafted onto the surface of the FST. Through photocatalytic experiments on the two types of composite materials synthesized, the results showed that the photocatalyst obtained by directly sensitizing Pc (FSTP) exhibited better performance on rhodamine B(RhB) removal than did the other photocatalyst using the silane coupling agent (FSTAP). Further mechanistic studies showed that directly sensitized FSTP exhibited more efficient photogenerated electron–hole pair separation, whereas FSTAP linked by a silane coupling agent created an additional transport distance that might greatly affect the photogenerated electron transport. Therefore, the dual-pathway research in this work provides new guidance for efficiently constructing phthalocyanine-sensitized TiO2 photocatalysts.